Taxol is naturally occurring compound that has significant promise as a chemotherapeutic drug. Current demand for taxol exceeds supply because the plant from which it is extracted is relatively rare and slow-growing, and the compound occurs at very low concentrations (.01%), mostly in the tree's bark. Alternative sources of taxol are required if future needs are to be met. The long-term objective of the Weyerhaeuser taxol project is to develop the genetic resources and production methodology necessary to cost-effectively produce taxol, and related taxanes, in a domesticated plant environment. This proposal outlines research that addresses 3 of the 8 key research needs required to meet this objective: 1) Estimating genetic parameters of taxane yields - A 2-tiered study using plant materials collected in natural populations of Taxus brevifolia, the Pacific yew, will define a) the heritability of taxane yields, b) the genetic relationship among various taxanes, and between taxanes and measures of growth, and c) levels of additive and non-additive genetic variance. The study will feature standard genetic test field designs for test materials that include populations, families within populations, and clones within families. 2) Estimating the magnitude and distribution of variation in taxane yields as a function of genetic, epigenetic and environmental factors - A series of factorial field studies using selected yew clones will be used to partition genetic and non-genetic sources of variation in taxane yields. 3) Estimate effects of post-harvest handling and storage on taxane yields - Two factorial experiments using selected yew clones will be used to evaluate storage duration effects on taxane yields. Results of these studies will define optimal genetic improvement and domestication strategies for the production of taxol.